Safety interlock for master controller



SAFETY INTERLOCK FOR MASTER CONTROLLER "ummm,

l .ym ha UIIIIIIIIIUIIH fmnmmemuun l l |.lllll United States Patent O 3,410,151 SAFETY INTERLOCK FOR MASTER CONTRLLER Donald W. Adams, Erie, John P. Nadzam and Ralph E.

Walter, North East, Ia., assignors to General Electric Company, a corporation of New York Filed Feb. 27, 1967, Ser. No. 618,788 Claims. (Cl. 74--483) ABSTRACT 0F THE DISCLSURE A safety interlock arrangement for a master controller of the type having two rotable cam-shafts arranged in parallel side-by-side relationship. The safety interlock includes a pivotally mounted locking pawl arranged to cooperate at one end with the end of a removable operating handle of one cam-shaft and at the other end with a notched disc having a rst not-ch on one .side of a diameter and a second notch on the other side thereof. The removable operating handle is arranged so that movement thereof `to initiate its removal operates to cause movement of the locking pawl in a direction to effect its engagement with the first notch of the notched disc with complete removal of the handle allowing for movement of the locking pawl in the opposite direction to effect its engagement with the second notch. The notched disc is secured to the other cam-shaft and the notches thereof are located so that engagement with the locking pawl can only be effected when the cam-shaft is in a predetermined position.

This invention relates to electric circuit controllers for electrically propelled vehicles and, more particularly, to a safety interlock arrangement therefor.

In electric circuit controllers for electrically propelled vehicles, such as diesel-electric locomotives, for example, it is customary to remove the operating handle from the controller to prevent unintentional movement of the vehicle as well as to prevent any meddlesome or malicious interference with the vehicle from resulting in its operation. Further, it is important that all controlled circuits be in preselected states of energization or deenergization when the operating handle is so removed.

It is .a primary object of this invention therefore, to provide a simple and reliable interlock arrangement which prevents operation of the controller upon removal of an operating handle and wherein removal of the operating handle can only be effected when the controller is in a predetermined operating condition.

It is a further object of this invention to provide an interlock arrangement for .an electric circuit controller which occupies a minimum of space and requires a minimum of movable parts.

Brieiiy stated, in accordance with one aspect of this invention, there is provided a new and improved safety interlock arrangement for an electric circuit controller of the type wherein tirst and second cam-shaft means are journaled in parallel, side-by-side relationship between spaced-apart end frame members. A iirst operating handle is provided operably associated with the rst cam-shaft means to provide for the rotation thereof and a second operating handle is provided operably associated with the second cam-shaft means for causing its rotation and which second operating handle is adapted for removal from the controller. There is also provided a locking means mounted for rotation with the iirst cam-shaft means and a locking pawl mounted for pivotal movement and with a iirst end thereof arranged for cooperation with an end of the second operating handle :and with a second end thereof arranged for cooperation with the locking means. A spring means is provided for urging the lirst ICC end of the locking pawl in the direction toward and into contact with the end of the second operating handle so that movement of the second operating handle to initiate removal thereof is operative to cause movement of the locking pawl in one direction and movement of the handle to complete its removal is operative to allow for movement of the locking pawl in the opposite direction. First and second means are provided on the locking means with the first means arranged for cooperation with the locking pawl to allow for movement of the pawl in the one direction only when the first cam-shaft means is in a predetermined position and with the second means arranged for cooperation with `the locking pawl when the locking pawl is moved in the opposite direction upon removal of the secon-d operating handle which cooperation is operative to prevent rotation of the first cam-shaft means.

The novel features believed characteristic of the inven-tion are set forth with particularity in the appended claims. The invention itself, however, together with further objects and advantages thereof as well as its organization and method of operation can best be understood by reference to the following description taken in conjunction with the accompanying drawing wherein the sole iigure thereof is an end view of an electric circuit controller.

Although specific terms are used in the following description for clarity in describing the invention, these terms are intended to refer only to the arrangement illustrated in the drawing and are not intended to define or limit the scope of the invention. Also, although the invention will be described in detail with the operating handle associated with the reverser cam-shaft means being removable, it is to be understood that either operating handle may be larranged to be the removable one as desired.

As is well known electric circuit controllers, often referred to in the art as master controllers are switching devices for controlling the application and direction of electric power for electrically propelled vehicles. A typical application -for such a master controller is on a dieselelectric locomotive to control the speed and direction of operation as well as to control dynamic braking if the locomotive is so equipped. Brietiy, the controller of the type with which the present invention is incorporated includes a throttle cam-shaft, .a reverse cam-shaft, cams, interlocks and switches. Conveniently, the various components of the controller are` assembled into an openmounted frame including spaced-apart end frame members suitably interconnected to side frame members. Since the general construction and organization of the basic componen-ts of the master controller per se are not part of the present invention and are well known in the art, a complete detailed description of such controller is not deemed necessary to a full understanding of the invention.

Accordingly, in the drawing only one end of an electric circuit controller, generally designated at 10, has been shown. Controller 10 includes a throttle cam-shaft means 11 having cams 12 suitably mounted thereon and a reverse cam-shaft means 14 having cams 15 similarly mounted thereon. Cam-shaft means 11 and 14 are arranged in parallel, side-by-side relationship and suitably journaled at one end frame member 17 and at the other end is a similar end frame member (not shown). The cams associated with cam-shaft -means 11 and 14 are operative to control the actuation of switch means (not shown) -operably associated therewith.

Since usually only a limited amount of travel is allowed for the throttle and reverser operating handles, shown at 18 and 20 respectively, to produce essentially 360 of -travel of their associated cam-shaft means, such cam-shaft means fare conveniently arranged to be driven through suitable gear means including sector gears 22 and 24, respectively. For some applications, of course, the `operating handles may be connected so as to directly drive their associated cam-shaft means.

To this end, throttle operating handle 18 is secured in any suitable manner, such as welding, to the sector gear 22 which is suitable rotatably mounted. Conveniently, sector gear 22 is secured in any suitable manner to a stubshaft 26 which is journaled at one end in end frame member 17 and at the other end in an extending support member 28. Sector gear 22 is arranged to mesh with a pinion gear 30 secured to the cam-shaft means 11. Similarly, sector gear 24, operably associated with handle 20, is suitably mounted for rotation with a shaft means 32 journaled at one end in end frame member 17 and at the other end in the extending support member 34. Sector gear 24 is arranged to mesh with the pinion gear 36 mounted on cam-shaft means 14.

From the foregoing, it will be evident that movement of the operating handles 18 or 20 causes rotation of the cam-shaft means operably associated therewith through their meshing sector and pinion gears which rotation is operative to cause the selective actuation of their camoperated switches to thereby control the electric circuits associated therewith in well known manner.

In accordance with this invention, a simple and foolproof safety interlock arrangement having a long operating lifetime is provided which interlock becomes operative upon removal of reverser operating handle 20 to prevent rotation of throttle cam-shaft means 11 but which handle removal can only be effected when cam-shaft means 11 and 14 are in predetermined relative positions; specifically, when throttle cam-shaft means 11 is in its idle position and reverser cam-shaft means 14 is in its off position represented in the drawing by operating handle 18 in the extreme down position and operating handle 20 in the mid-position.

To this end, reverser operating handle 20 is arranged to be readily removable. This may be conveniently accomplished, as shown, by providing handle 20 with a pin 40 adapted to be positioned in a locking slot 42 provided therefor in a suitably slotted block 44. Removal of handle 20 may then be easily accomplished by causing such handle to be moved inwardly and thereafter turned on its own axis, so thatl pin 40 disposed therein will be released from locking slot 42 in block 44 which is mounted to the hub of sector gear 24. Block 44 is provided with a suitably enlarged bore which allows the handle 20 with its extending pin 40 to pass through and be completely withdrawn from the controller.

A locking pawl 46 is pivotally mounted and adapted to cooperate at one end with the inner end 48 of reverser operating handle 20 and at the other end with a suitable locking means, shown as a notched disc 50, which is secured to cam-shaft means 11 for rotation therewith. For example, the pivotally mounted locking pawl 46 is arranged with a first end 52 disposed for cooperation with the end 48 of the handle 20, and a second end 54 of the locking pawl is arranged for cooperation with the locking means so that movement of the handle 20 in a direction to begin the removal thereof (inwardly for the arrangement illustrated) operates to cause movement of locking pawl 46 in one direction and movement of handle 20 in the direction to complete its removal operates to allow movement of locking pawl 46 in the opposite direction. Thus, locking pawl 46 may be arranged for movement parallel with or perpendicular to the plane of the end frame member 17.

Conveniently, locking pawl 46 may be mounted, as illustrated, for movement parallel with the plane of end frame member 17 by being rotatably mounted on an extension of the shaft of cam-shaft means 14 so that the end 52 thereof cooperates with the end 48 of operating handle 2i) and the end 54 thereof is adapted to cooperate with the locking means. That is, the locking means is provided with first and second means which selectively cooperate with the locking pawl 46 when the pawl is moved in different directions. Thus, when the locking means is a notched disc 50 as illustrated, the first means may be the notch 68 thereof which is disposed on one side of a diameter of disc 50 and the second means may be the notch 66 disposed on the other side of such diameter. Accordingly, the notch 68 is arranged for engagement with the end 58 of the locking pawl 46 to allow for movement of such locking pawl in one direction (clockwise for the arrangement shown) only when the first camshaft means 11 is in a predetermined position since only then is notch 68 in alignment with end 58. Also, the second means provided by notch 66 is arranged for engagement with the end 59 of locking pawl 46 when such locking pawl is moved in the opposite direction (counterclockwise for the arrangement shown); engagement of the end 59 with notch 66 being operative to prevent rotation of the firs-t cam-shaft means 11.

Movement of locking pawl 46 in the direction to cause engagement of its end 59 with the notch `66 is provided by a suitable bias means, shown as the spring means 60. Spring means 60 is disposed as shown between the end 52 of locking pawl 46 and a suitable member 64 which extends from end frame member 17 The spring means 60 urges the end 52 toward the end 48 of removable handle 20 which end is so located that as long as handle 20 is in place, locking pawl 46 is in its inoperative position with the ends 58 and 59 out of engagement with the notched disc 50.

The end 52 of locking pawl 46 is provided with a suitable contour shown as concave recess 70, so that movement of handle 20 during operation does not cause sufticient movement of locking pawl 46 to cause engagement of either of the ends 58 or 59 with the notches 66 or 68 of notched disc 50. That is, spring means 60 causes the end 52 of locking pawl 46 to be urged into contact with the end 48 of operating handle 20 and during operating movement of handle 20 the ends 58 or 59 of locking pawl 46 must not be caused to be moved into engagement with the notches `of notched disc 50, which would prevent rotation of cam-shaft means 11. To allow for free movement of handle 20, the end 48 thereof may be provided with a suitable roller so as to be in rolling rather than sliding contact with the surface of concave recess 70.

It is also desirable to provide means to assure that reverser operating handle 20 cannot be moved readily in a continuous motion between its positions on either side of the off position. For example, typically one direction of movement of reverser operating handle 20 from the off position provides for forward motoring and braking while the other direction of movement provides for reverse motoring and braking. Obviously, it is not desirable to allow for an inadvertent rapid change from the forward to the reverse direction.

To this end, a locking ring is provided having a Z-type slot 82 therein in which an undercut section 84 of operating handle 20 moves. Thus, movement of operating handle 20 from the off position requires an additional movement to cause it to clear the shoulder of the Z-type slot 82. For example, movement of handle 20 from the off position toward a downward position (for the orientation of the controller shown) must be accompanied by movement thereof outwardly of the plane of the drawing so that the shaft of the handle can clear the shoulder of the Z-type slot. Similarly, movement of handle 20 from the olf position toward an upward position must be accompanied by movement thereof into the plane of the drawing to allow it to clear such shoulder.

In operation, the controller is arranged to be locked by removal of reverser operating handle 20. This is accomplished -by pushing handle 20 inwardly against the force of spring means 60 until the pin 40 is clear of the locking slot 42 in block 44, after which handle 20 is rotated on its own axis for removal through the enlarged bore provided in block 44. Observation of the drawing will illustrate, however, that unless the notch 68 of notched disc 50 is in alignment with the end 58 of locking pawl 46, handle cannot be pushed inwardly a sufficient distance to allow pin 40 to clear the locking notch 42 thereby preventing rotation of handle 20 on its own axis. Accordingly, the notch 68 is arranged to be in alignment with the end 58 of locking pawl 46 only when the throttle cam-shaft means 11 is in the idle position. Also, to assure that reverser operating handle 20 is in its 0E position when it is removed, an undercut portion 84 of handle 20 is arranged to move in the Z-type slot 82 of the locking plate 80. Slot 82 is arranged to be large enough to allow for free movement of the undercut portion 84 of handle 20 but not large enough to allow the full dimension of the shaft thereof to pass except at the mid-position of the slot 82 which represents the off position of the reverser cam-shaft means 14.

Accordingly, only when operating handle 20 is in the off position and throttle operating handle 18 is in the idle position, is it possible to move operating handle 20 inwardly a sufiicient distance to allow pin 40 to clear the slot 42 and be rotatedon its own -axis for removal from the controller. Also, since the end 58 of locking pawl 46 is in alignment with the notch 68 of ldisc 50, locking pawl 46 is allowed to be rotated clockwise by the action of the end 48 of handle 20 as the handle is pushed inwardly. The pawl 46 may be rotated until the end 58 thereof fully engages the slot 68 which is sufficient to allow the pin 40 to clear the slot 42. A 90 rotation of handle 20 on its own axis places pin 40 in the enlarged bore portion of the block 44 and the handle may be merely withdrawn.

Once reverser operating handle 20 has been removed, the end 48 thereof is no longer in contact with the end 52 of locking pawl 46 so that spring means 60 causes counter-clockwise rotation of locking pawl 46. This counterclockwise rotation causes the end 59 of locking pawl 46 to engage the notch 66 of notched disc 50 and to remain so engaged by action of the spring means 60 until handle 20 is replaced. With the end 59 of locking pawl 46 engaged in the notch 66 of notched disc 50, cam-shaft means 11 is locked thereby and is prevented from being rotated without application of excessive force to the handle 18. As shown, notch 66 is made smaller than the end S8 of locking pawl 46 so that engagement between notch 66 and end 58 is prevented under the condition when notch 66 rather than notch 68 is in alignment with such end. Removal of handle 20 is therefore not possible in such a case.

From the foregoing description, it will be appreciated that there has been provided a simple interlocking arrangement which is rendered operative upon removal of the reverser operating handle 20 which permits the spring biased locking pawl to engage the notch 66 of the notched locking disc 50 thereby locking up the throttle cam-shaft means 11. Since the reverser operating handle 20 must be free to be pushed inwardly, a sufcient distance to allow it to clear a locking slot so that the handle may be rotated on its own axis, such handle removal is possible only if the throttle cam-shaft means is in the idle position and the reverser camshaft means is in the off position. 'If the throttle camshaft means is out of position, the notches of the notched locking disc 50 are not aligned with the ends of the pawl 46 thereby restricting the inward travel of the relverser operating handle 20,Also, a locking ring 80 is provided having an opening therein for the handle 20 which is so dimensioned that the handle 20* can only be moved inwardly when it is in its olf position.

While only preferred features of the invention have been shown and described by way of illustration, many changes and modifications will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. -In a revolving cam electric circuit controller of the type wherein first and second cam-shaft means are arranged 4in parallel, side-by-side relationship 'and journaled in spaced-apart end frame members and wherein at least one of the operating handles for causing rotation of said cam-shaft means is removable, the combination with such controller of interlock means for preventing rotation of one cam-shaft means upon removal of the operating handle associated with the other cam-shaft means and wherein said handle can be removed only when said first and second cam-shaft means are in predetermined positions comprising:

(a) locking means mounted on said first cam-shaft means for rotation therewith;

(b) a pivotally mounted locking pawl having one end arranger for cooperation with an end of the -removable handle associated with said second camshaft means and the other end arranged for cooperation with said locking means so that one por tion of the movement associated with the removal of said handle is operative to cause movement of said locking pawl in one direction and another portion of the movement associated with the removal of said handle is operative to allow for movement of said locking pawl in the opposite direction;

(c) spring means for urging movement of said locking pawl in said opposite direction; and

(d) first and second means associated with said locking means, said first means being arranged and adapted for cooperation with said locking pawl to allow for movement thereof in said one direction only when said rst cam-shaft means is in a predetermined position and said second means being arranged and adapted for cooperation with said locking pawl when said locking pawl is allowed to move `in said opposite direction and being operative to prevent rotation of said first camshaft means.

2. The combination of claim 1 wherein said locking means is a notched disc and said first and second means associated therewith are respectively a first notch disposed on one side of a diamter of said disc and a second notch disposed on the other side thereof.

3. The combination of claim 2 wherein said locking pawl is pivotally mounted for rotation labout an axis perpendicular to the plane of said notched disc.

4. The combination of claim 3 wherein said locking pawl is provided at one end with a concave recess adapted to be engaged by said one end of said removable operating handle so that normal operating movement of said handle does not result in any significant movement of said locking pawl and provided at its other end with spaced-apart leg portions, one of said leg portions having its free end directed and dimensioned to be engaged within said first notch when said locking pawl is caused to be removed in said one direction and the other leg portion having its free end directed and dimensioned to be engaged within said second notch when said locking pawl is allowed to move in said opposite direction.

5. The combination of claim 4 wherein the free end of said first leg portion is dimensioned so as to be larger than the opening provided by said second notch.

6. The combination of claim 2 wherein said locking pawl is mounted for rotation about an extending end of the shaft of said second cam-shaft means.

7. The combination of claim 2 wherein said removable handle is arranged to be removed by a first movement portion parallel with the longitudinal axis thereof and in a direction toward said one end thereof, a second movement comprising a rotation about said longitudinal axis and withdrawal of said `handle by movement parallel with said longitudinal axis.

8. The combination of claim 7 wherein movement of said handle in the direction toward said one end thereof is operative to cause movement of said locking pawl in said one direction and withdrawal of said handle is operative to allow for movement of said locking pawl in said opposite direction.

9. The combination of claim 2 wherein said first and second notches are disposed for cooperative engagement with said locking pawl only when sai-d rst cam-shaft means is in a predetermined position.

10. The combination of claim 9 wherein said ramovable handle means is operably associated with means to prevent said one portion of the movement associated with the removal of said handle unless said second camshaft means is in a predetermined position.

References Cited UNITED STATES PATENTS 532,538 1/1895 Davis 20G-50.3 548,599 10/1895 Valley ZOO-50.3 1,160,821 11/1915 Beane 296-50 FOREIGN PATENTS 90,405 12/ 1922 Austria.

FRED C. MATTERN, JR., Primary Examiner.

C. F. GREEN, Assistant Examiner. 

